Food Iron Absorption in Man APPLICATIONS OF THE TWO-POOL EXTRINSIC TAG METHOD TO MEASURE HEME AND NONHEME IRON ABSORPTION FROM THE WHOLE DIET

Abstract

ABS TRA CT A new radioisotope method to measure iron absorption from the whole diet was used in this study. The method is based on the concept that food iron is absorbed from two pools, the heme iron pool and the nonheme iron pool, which can be especially labeled with two radioiron isotopes given as hemoglobin and as an iron salt. The purpose of this study was to test the accuracy of this two-pool extrinsic tag method.The meals served were composed as an average of 6 wk consumption in the present material of 32 young enlisted men. The mean and total heme and nonheme iron absorption in all the 32 young men was 1.01±0.11. This figure agrees well with the mean daily losses expected for this group of subjects (1.0 mg). The conclusion can therefore be made that there are no major systematic errors of the present method to measure the total iron absorption from a mixed diet.In one series a comparison was made of the absorption of heme and nonheme iron from the meals. A significant correlation between the absorption of the two kinds of iron was found. However, a much greater fraction of the heme iron was absorbed (37%) than of the nonheme iron (5%).The absorption both from breakfast and lunch was in two series found to give a good prediction of the total daily nonheme iron absorption. One series was designed to compare the effect of two levels of iron fortification. There was a significant increase in iron absorption when the level of iron fortification of the meals was increased.

Inositol phosphates with different numbers of phosphate groups influence iron absorption in humans

“…Absorption of the reference doses was measured by whole-body counting 2 wk later (see below). All procedures and methods of calculation were described previously by Björn-Rasmussen et al (16) and Hallberg (17).…”

Iron Absorption from Maize

“…The percent absorption of non heme iron is much lower than that of heme iron and may be affected by a number of components in the diet [3].…”

Bioavailability of elemental iron powder in white wheat bread

“…This caveat is not evident in traditional radioiron bioavailability studies that utilize an extrinsic tag or tracerFa minute amount of added radioactive ironFthat is assumed to enter the common pool and behave identically to the dietary soluble nonheme iron therein. This has been well demonstrated for the native iron in many foodstuffs and soluble iron salts such as ferrous sulfate (Layrisse et al, 1969(Layrisse et al, , 1973Bjorn-Rasmussen et al, 1972, 1974Cook et al, 1972).…”